Managing for Diversity
Insurance for the Future Forest
Editor’s Note: Ben Farina, a forester in the White Mountain National Forest, was recommended to From the Ground Up by Tony D’Amato. In this lively essay, Ben describes the extra tweaking of a partial timber harvest, aimed at securing regeneration of red oak and white pine—unusual species in the Whites, which may become more common if kept in the mix. This speaks to the ecological forestry goal of maintaining diversity at the landscape scale, in the face of an uncertain future. - Brian Donahue
Every great asset in America needs an insurance policy: manage forests for diversity
I’ve always been a believer that a walk in the woods gets the creative juices flowing. Today, I need every drop. It’s a damp day in the White Mountain National Forest, and the blonded white ash trees that dominate this northern hardwood stand jump out like orange highlighters. The beech understory is thriving in the newly opened canopy gaps at the expense of the dying ash. Concerning? No doubt. Add beech leaf disease to the mix of potential threats, and all I can think is that I wish I had more to work with. If not ash or beech, what’s the future here? What’s the next “big thing” to affect our forests? As I think about a management approach to maintain a functional stand, I hear something over my iPhone speaker that says, “Every great asset in America has an insurance policy.”
“National Forests are unquestionably one of America’s greatest assets. But what does the application process look like for an insurance policy on a forest? The answer is simpler than you might think: Manage for diversity.”
Full disclosure: I am both a forester and a football fanatic who enjoys a thought-provoking podcast in the woods. This segment referred to drafting a backup quarterback years before you plan on needing one, for an added level of security. But there seemed to be a takeaway. If you own a house or a car, you likely have insurance that builds resilience in the midst of uncertainty, allowing you to maintain the benefits of the asset should something unforeseen occur. Why not expand this concept to forests? After all, National Forests are unquestionably one of America’s greatest assets. But what does the application process look like for an insurance policy on a forest? The answer is simpler than you might think: Manage for diversity.
Forest dynamics are fascinating. Spongy moth populations are regulated by drought, and population spikes can be detrimental to some tree species and less impactful to others. A strong wind event can blow down an overstory, regardless of species, and pose little damage to an understory. Good luck getting a fire to burn through a young hardwood stand, while in older stands some tree species have evolved to welcome wildfire at the expense of competitors, increasing its frequency. The list is never ending, revealing the strengths and vulnerabilities that a forest might hold. The challenge is, they haven’t yet invented the crystal ball capable of predicting these damaging events in time for forest managers to react. Putting your eggs into too few wooden baskets by managing for homogeneity can leave your forest susceptible to that unknown future stressor.
Back to the insurance policy. What does that mean in the context of forests? To address uncertainties, a diversified approach to forest management adds a level of resilience, helping to maintain the benefits that our forests provide. An insurance policy. Diversity (or complexity in terms of forest structure) reflects the need to create and maintain differences in species, age classes, and canopy openings. This approach builds resilience by reducing vulnerability to disturbance. It aids recovery by maintaining multiple seed sources and a regeneration layer that is ready to react. It can be applied both within individual stands and across a forest of thousands of acres. At a landscape level, the distribution of forest developmental stages and cover types present opportunities to correct an overabundance of a single condition. The same is true to a finer degree at the stand level, presenting opportunities to improve habitat qualities like deadwood or large diameter trees.
This past summer’s work highlighted my favorite example of using a diversified ecological approach. Red oak and white pine-dominated stands become few as you get into the mountains in New Hampshire where northern hardwoods—accompanied by spruce, fir, and hemlock—are the most abundant species. In fact, oak/pine forests make up only one percent of the acreage on the White Mountain National Forest. Sustaining oak/pine stands as an uncommon habitat type on the landscape is a goal, but doing so requires active management. Many of these stands originated as relics of agriculture, which is difficult to replicate. These forests are still ecologically young from a developmental standpoint (80–100 years). If left to manage themselves, lack of understory light would cause these stands to lose the oak/pine components over time, as they revert to a forest dominated by northern hardwoods, the pre-settlement condition. Hence, if a management aim is more complex oak/pine stands that include multiple age classes, we need to recognize that getting oak/pine regeneration is difficult. Blame the lack of disturbance, or the pesky beech stems that shade out the understory, or the palatability of red oak seedlings and the propensity of deer to find them. The challenges with restoring young oak/pine conditions are well documented.
“Putting your eggs into too few wooden baskets by managing for homogeneity can leave your forest susceptible to that unknown future stressor.”
In the stand we were assessing and treating, the canopy cover had been, prior to harvest, heavy to red oak with a mix of other hardwoods and a few white pines sprinkled in. A partial cut in the fall of 2021, during a bumper acorn crop, paved the way for abundant red oak and white pine regeneration. Over half of the trees were retained to shield scattered clusters of white pine regeneration during the harvest. Given the regeneration success, this presented an adaptive opportunity for careful hand-felling, catering to the sun-loving traits of oak and pine while leaving other areas with a closed canopy, to be populated by shade-tolerant spruce and hemlock. The irregular spatial canopy pattern that we created this way reduces vulnerability to disturbance, while allowing species suited to either more sunlight, or more shade, to thrive.
As an added bonus, post-harvest felling created another opportunity for a practice you won’t see in traditional forestry: morticulture, or the creation of deadwood. Typical forest management tends to target less vigorous trees for harvest. This is generally good practice, but it prevents trees from naturally dying and becoming important habitat features such as standing dead trees (snags) or downed logs, critical elements of forest complexity. This stand was no exception. It now lacked deadwood. So, we carefully put some trees on the ground.
White pine release and deadwood creation. Photo © Ben Farina
This was a strong deviation from a timber-focused forestry approach—purposely cutting trees only to let them rot in the woods. Why wouldn’t you just cut them during the harvest? Maybe. Given the regeneration difficulties, the likelihood of damage from the added felling/skidding wasn’t worth the risk. This method was certainly unusual for us, but so was this stand in the big picture. This outside-the-box approach was critical in meeting our goal. Thoughtful hand felling became a strategic release, simultaneously enhancing structural complexity and deadwood legacy habitat. We even girdled a few standing trees to create snags (Photo B).
Snag creation. Photo © Ben Farina
As I walked out of the woods, I was feeling optimistic about this stand’s resiliency. Success was reached in maintaining an uncommon forest type equipped with growing conditions to boost residual tree health. A new cohort was established that will thrive in the variably open light environment. The stand itself is less dominated by red oak, due to favoring less abundant species as seed sources. I counted fourteen tree species present, lowering vulnerability and providing a pathway to recovery should something harmful to oak come along. The added deadwood legacies also give a boost to habitat quality.
With complexity attained and a profitable timber harvest achieved, this management tactic reached environmental, ecological, and socially-desired outcomes, and it presents a good example of ecological forestry.
Now, with payment processed and effective date passed, this insurance policy is live. And obtaining one has never felt so good!
Ben Farina is a silviculturist with the U.S. Forest Service, White Mountain National Forest (WMNF), Pemigewasset Ranger District. A native of New Hampshire, Ben was trained in forestry at UNH. Says Ben: “I have always been someone who loves teamwork and problem-solving. I look at ecosystem management as a puzzle with many pieces in place but also some still missing. It is up to us as managers to figure out where the pieces best fit.” Ben resides in Campton, smack in the middle of his home state.